pg_index

The pg_index catalog provides information about indexes.

Column name	Data type	Description
`indexrelid`	`oid` (references `pg_class.oid`)	The OID of the `pg_class` entry for this index.
`indrelid`	`oid` (references `pg_class.oid`)	The OID of the `pg_class` entry for the table to which the index belongs.
`indnatts`	`int2`	The total number of columns in the index, including both the key and assigned attributes.Note: `indnatts` stores the same count number that appears in `pg_class.relnatts` for the index relation.
`indnkeyatts`	`int2`	The number of key columns in the index, excluding any columns that do not participate in index semantics.
`indisunique`	`bool`	Specifies whether this is a unique index (`TRUE`) or not (`FALSE`).
`indnullsnotdistinct`	`bool`	Specifies whether `NULL` values are considered distinct (`FALSE`) or equal (`TRUE`).
`indisprimary`	`bool`	Specifies whether the index represents the table’s primary key (`TRUE`) or not (`FALSE`). Note: `indisunique` is always `TRUE` when `indisprimary` is `TRUE`.
`indisexclusion`	`bool`	Specifies whether the index supports an exclusion constraint (`TRUE`) or not (`FALSE`).
`indimmediate`	`bool`	Specifies whether uniqueness checks are enforced immediately on insertion (`TRUE`) or not (`FALSE`). Note: If `indisunique` is `FALSE`, this option doesn’t apply.
`indisclustered`	`bool`	Specifies whether the table was last clustered on the index (`TRUE`) or not (`FALSE`).
`indisvalid`	`bool`	Specifies whether the index is valid for queries (`TRUE`) or not (`FALSE`). Note: `FALSE` indicates the index may be incomplete and cannot safely be used.
`indcheckxmin`	`bool`	Specifies whether queries must avoid using this index until the `xmin` of the `pg_index` row is below their `TransactionXmin` (`TRUE`) or not (`FALSE`).
`indisready`	`bool`	Specifies whether the index is ready for inserts (`TRUE`) or not (`FALSE`).
`indislive`	`bool`	Specifies whether the index is live (`TRUE`) or in the process of being dropped (`FALSE`).
`indisreplident`	`bool`	Specifies whether this index has been chosen as the “replica identity” (`TRUE`) or not (`FALSE`).
`indkey`	`int2vector` (references `pg_attribute.attnum`)	The array of `indnatts` values indicating which table columns are indexed. Key columns come before included columns. `0` indicates an expression instead of a simple column.
`indcollation`	`oidvector` (references `pg_collation.oid`)	The OID of the collation to use for each key column. The value is `0` if the column type is not collatable.
`indclass`	`oidvector` (references `pg_opclass.oid`)	The OID of the operator class used for each column.
`indoption`	`int2vector`	The array of per-column flag bits for key columns.
`indexprs`	`pg_node_tree`	Expression trees (in `nodeToString()` representation) for index attributes that are expressions (where `indkey` is `0`). The value is `NULL` if all attributes are simple columns.
`indpred`	`pg_node_tree`	An expression tree (in `nodeToString()` representation) for a partial index predicate. The value is `NULL` if it is not a partial index.